Kathleen Markowski Petrillo

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Kathleen Markowski Petrillo — patent litigation summary

Specialty / focus. Petrillo is a registered patent attorney whose practice centers on chemical, life-sciences, and energy technologies. Her background is in chemical engineering (B.S., University of Pittsburgh, 1987), and Lewis Rice's Chambers USA profile describes her counseling clients in pharma, biotech, medical, energy, oil and gas, agricultural, and food science — spanning small-molecule pharmaceuticals, polymeric formulations, diagnostic assays, MRI/optical contrast agents, herbicide formulations, fuel cells and flow-battery membranes, and carbon-capture materials, plus more mechanical consumer goods such as kamado grills. She also prepares infringement/validity opinions and Paragraph IV / Hatch-Waxman opinions.

Side preference. Her tracked district-court appearance is on the defense side: Midwest Energy Emissions Corp. v. Ameren Corp. et al. (S.D. Iowa / E.D. Mo., MDL No. 3132), where she represents Ameren Corp. and Union Electric Co. against Birchtech Corp. f/k/a ME2C. The broader record shows she works both sides of the "v.": she has acted as Patent Owner counsel defending patents in IPR (e.g., Scepter Canada Inc. v. No Spill Inc., IPR2020-00360; Arthrex, Inc. v. P Tech, LLC, IPR2022-00717/00786/00787), while her district-court litigation work has been for accused infringers. Her practice is anchored in prosecution, portfolio development, and enforcement rather than in NPE-side assertion — the small tracked sample (0 plaintiff / 1 defendant) should not be read as a definitive side profile, since docket coverage here is only one case.

Firm context. She is at Lewis Rice LLC in St. Louis, which she joined in March 2020 from Stinson LLP, along with Robert M. Evans, Jr. and Michael J. Hartley (Stinson had absorbed Senniger Powers in 2018). She was previously a partner at Senniger Powers (partner from 1998, and later head of its patent practice), before that an associate at Arnold, White & Durkee in Chicago, and earlier a patent examiner at the USPTO and a patent agent while in law school. Her tracked appearance in the ME2C matter is listed as of counsel; the firm's Chambers profile identifies her as a Practice Group Leader for the intellectual property group, so her current title at the firm should be confirmed directly.

Notable matters, PTAB, and credentials. In P Tech, LLC v. Arthrex, Inc. (Fed. Cir. No. 24-1265), she was on the Lewis Rice team representing patent owner P Tech; the Federal Circuit affirmed the PTAB in a nonprecedential Rule 36 judgment on July 9, 2025 — an adverse outcome for her client. She appears repeatedly in PTAB filings, including as backup counsel on the ME2C/Birchtech IPR petitions and patent-owner responses in 2025, so IPR work is a regular part of her docket. She is routinely ranked in Chambers USA (Intellectual Property – Missouri) and Best Lawyers, which named her its 2017 "Lawyer of the Year" for both Patent Law and Patent Litigation. Bar/education: admitted in Illinois (1993) and Missouri (1994); J.D., The John Marshall Law School (1993, cum laude); registered before the USPTO (Reg. No. 35,076).